Short answer:
Unfortunately, it is not possible to get the full list of previous locations back
A long explanation:
Significant Locations have been changed. Before you could see tracks of all the places you had been, but today you can only see a few. The rest is "hidden". I'm a bit unsure if it was changed in iOS14, or iOS15
Although it was a smart function to be able to back track one's locations, that is not the point of Significant Locations. The purpose of the function is to track your locations in the background, in order to provide you with relevant information and navigation routes when you need them. So it was never meant to be a back track list.
The function could in principle be abused, if a malicious person has the passcode for the phone, they could previously see all the owner's locations. I don't know what Apple is thinking, but I would imagine that is why the feature has been changed.
Maybe a solution:
The Google Maps app offers Location History, which can more or less do the same + you can see the route you have moved on. It might be an option for you if you want to back track.
Google Maps is free and can be downloaded from the App Store.